Personal computers have become mainstream computing devices for the past two decades. One of the core components of a personal computer whether desktop or laptop is a mother board, which is the central or primary circuit board providing attachment points for one or more of the following: processor (CPU), graphics card, sound card, hard disk drive controller, memory (Random Access Memory (RAM), Read-Only Memory (ROM)), and other external devices. Traditionally, hard disk drives have been used as a data storage in a computing device. With advance of non-volatile memory (e.g., flash memory), some attempts have been made to use non-volatile memory as the storage. One form of flash memory is referred to as Single-Level Cell (SLC) flash memory, in which each flash memory cell stores two states or one bit of information. Another form is referred to as Multi-Level Cell (MLC) flash, which can store more than two states of information, for example, four states or two bits. Because the MLC flash can hold more information than the SLC flash in a same size chip or integrated circuit, it is therefore more economic to use the MLC flash to create a storage device for replacing the traditional hard disk drive.
However, there are problems associated with using flash memory. One of the main problems is that the life span of the flash memory is measured by number of times that the flash memory has been written (i.e., programmed) and erased. This problem has a relatively large impact to the MLC flash, because a typical life span is an order of magnitude lower than that of the SLC flash. The prior art solution is to use wear leveling technique to prolong the life span. But such solution is not sufficient for using MLC as data storage.
Therefore it would be desirable to provide a non-volatile memory device (NVMD) to improve the endurance of MLC flash memory.